Official Answer
Answer
Hydrogen embrittlement occurs during the acid pickling or electroplating (e.g., Zinc plating) of high-carbon steel springs. Atomic hydrogen ($H$) diffuses into the steel's grain boundaries. Under tensile stress, these hydrogen atoms migrate to the tips of micro-cracks, reducing the cohesive strength of the lattice and causing brittle fracture at stresses far below the yield strength. To mitigate this, springs must be 'baked' immediately after plating (typically at $375^{\circ}F$ for 4 to 24 hours depending on thickness) to drive out the trapped hydrogen. Failure usually presents as a clean, 'glass-like' fracture surface with no evidence of plastic deformation.
